Digital Remote Thermometer Receiver

Created: Feb 21, 2014

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Description

No description available.

Summary

This device is a receiver circuit for a Digital Remote Thermometer. The thermometer operates by converting the sensor’s output voltage, which is calibrated and proportional to the measured temperature, to output cycles. The output cycles are transmitted in the supply cables and the receiver section counts the cycles from the transmitter; the calibrated counting are then displayed in the 7-segment LED displays.

The receiver circuit uses the 4093 Quad two input Schmitt NAND Gate IC as one of the logic components. Another component used is the 74HCT4520 dual 4-bit synchronous binary counter which is a high-speed Si-gate CMOS device. It has a dual 4-bit internally synchronous binary counters with an active high clock input and an active low clock input and buffered outputs. In this circuit, only two output levels from each of the binary counters, are utilized and the rest are connected to ground. The 74HCT4520 is coupled to the 74HCT4017 5‑stage Johnson decade counter for synchronized clocking. The MC14553B 3-digit BCD counter is also used in this circuit. The MC14553B consists of three negative edge triggered BCD Counters that are cascaded synchronously. In this circuit, the MC14553B controls the most significant (leftmost) value of the thermometer display. Lastly, the HEF4511B BCD to 7-segment BCD decoder is coupled to the MC14553BCP 7-segment displays. The HEF4511B decoder controls each of the displays to indicate the calibrated temperature.

The circuit is ideal for room temperature measurement. It displays the temperature in centigrade within the range of 00.0 to 99.9 degrees centigrade. Adjustments in the circuit are necessary to change the temperature ranges that can be accommodated by the circuit.